Garret Schuelke's poem is only three short lines long, and it says almost nothing: the sun is going down. That plainness is the point. With so few words, nothing competes with the moment itself, and the reader is left to simply watch it happen.
The speaker doesn't tell us how they feel, and there's no description of colors or sky. Judging by the stillness of the lines, they seem calm and attentive, maybe a little quiet or wistful, the way people often are when a day winds down. The line breaks matter here. Each line gives one small step, "The sun / is going / down," so the sentence itself seems to sink slowly, mirroring the sunset. You can almost feel the pause at the end of each line, like the light dropping a bit lower each time.
The mood is peaceful and contemplative. What the poem does best is leave room: you can fill the silence with your own evening, whether it feels restful, lonely, or something in between.